Adjusting heater current to reduce read transducer asymmetry

Abstract

An asymmetry is determined of a signal generated by a read transducer in proximity to a changing magnetic field of a magnetic media. In response to determining the asymmetry of the signal, a current flowing through a heater of the read transducer is adjusted to cause a change to a magnetic field generated by the current. The change to the magnetic field generated by the current reduces the asymmetry of the signal.

What is claimed is: 
     
       1. A method comprising: determining asymmetry of a signal generated by a read transducer;
 adjusting a current flowing through a heater associated with the read transducer to produce a magnetic field that reduces the asymmetry of the signal generated by the read transducer after determining the asymmetry. 
 
     
     
       2. The method of  claim 1 , wherein adjusting the current flow comprises changing a direction of the current flow. 
     
     
       3. The method of  claim 1 , further comprising determining the asymmetry via a transfer curve test. 
     
     
       4. The method of  claim 3 , wherein the transfer curve test involves placing the read transducer in a variable magnetic field during manufacture of a device that comprises the read transducer. 
     
     
       5. The method of  claim 1 , further comprising determining the asymmetry of the signal based on an output of the read transducer during operation of a data storage apparatus that comprises the read transducer. 
     
     
       6. The method of  claim 1 , wherein the heater is used to adjust a distance between the read transducer and a magnetic media. 
     
     
       7. The method of  claim 1 , wherein the read transducer produces the signal in response to being proximate to a changing magnetic field of a magnetic media. 
     
     
       8. The method of  claim 1 , wherein the heater comprises a joule heater. 
     
     
       9. The method of  claim 1 , wherein adjusting the current flow comprises blowing one or more fuses of two or more conductive paths that couple the heater and a power source that provides the current. 
     
     
       10. An apparatus comprising:
 a read transducer that generates a signal in response to reading a magnetic media; and 
 a heater coupled to a power source that adjusts a current flowing through the heater to produce a magnetic field that reduces an asymmetry of the signal of the read transducer after determining the asymmetry of the signal. 
 
     
     
       11. The apparatus of  claim 10 , wherein the power source adjusts the current flow by changing a direction of the current flow. 
     
     
       12. The apparatus of  claim 10 , wherein the asymmetry is determined via a transfer curve test. 
     
     
       13. The apparatus of  claim 10 , further comprising a controller configured to determine the asymmetry of the signal based on an output of the read transducer during operation of the apparatus and adjust the current flowing through the heater via the power source in response thereto. 
     
     
       14. The apparatus of  claim 10 , further comprising two or more conductive paths coupled between the heater and the power source, and wherein one or more of the conductive paths comprises a fuse, and wherein the current flow is adjusted by blowing at least one of the fuses. 
     
     
       15. The apparatus of  claim 10 , wherein the heater comprises a joule heater. 
     
     
       16. A system comprising:
 a read transducer that generates a signal in response to being in proximity to a magnetic media; 
 a heater; and 
 a controller coupled to the heater, the controller including circuitry configured to determine asymmetry of the signal based on an output of the read transducer during operation of the system and that adjusts a current flowing through the heater to alter a magnetic field that encompasses at least the read transducer, wherein the altered magnetic field reduces the asymmetry of the signal generated by the read transducer. 
 
     
     
       17. The system of  claim 16 , wherein the controller adjusts the current flow by changing a direction of the current flow. 
     
     
       18. The system of  claim 16 , wherein the heater comprises a joule heater that is used to adjust a distance between the head and the magnetic media. 
     
     
       19. The system of  claim 16 , further comprising two or more conductive paths coupled between the heater and the controller, wherein one or more of the conductive paths comprises a fuse, and wherein the current flow is adjusted by blowing at least one of the fuses.